A database is a system for storing and managing data. A database may store quantities of data which are potentially very large. Diverse types of data may be stored at the same database. In most databases, relationships between different elements of data stored at the database exist. Notably, such relationships may exist between data elements having different data types. To allow systems external to the database to access data located at the database, databases generally include functionality to process queries. A query is a request to retrieve specified data located at a database and to transmit the retrieved data to the entity which submitted the query.
Many databases known in the art organize data according to a hierarchical paradigm. A database organizing data in this manner is known as a hierarchical database. In a hierarchical database, parent-child relationships exist between different data elements stored at the database. A given data element may have a plurality of data elements as children. However, a given data element may have at most one data element as a parent. These parent-child relationships may define one or more tree structures. It is emphasized that a data element may have a parent, a child, or both which is of a different data type.